Groundwater Contamination Modeled to Subside by 2052
Environmental consultants Anderson Mulholland & Associates propose allowing the contaminated Topps site to mitigate naturally
A seven-year long investigation into tetrachlorethylene (PCE) contamination of the soil and groundwater at the former Topps Dry Cleaners site has determined that the scope of contamination is decreasing naturally over time and should subside by 2052, environmental consultants informed the public Tuesday at an open meeting.
Ellen Ivens of Anderson Mulholland & Associates (AMAI), the environmental firm hired to conduct Topps' site investigation, proposed establishing a Classification Exemption Area (CEA) -- a zone where groundwater use is restricted until safety standards are met -- while allowing the contaminated groundwater to attenuate naturally over the next forty years.
AMAI will continue to monitor PCE contamination levels in the groundwater and indoor air every two years as long as the remediation is ongoing, to ensure the passive remediation process is working as expected, Ivens said. In the event that PCE contamination levels reverse and begin to elevate over time, AMAI will step in and take the appropriate measures to mitigate the problem, likely through some form of enhanced remediation.
PCE is a common dry cleaning solvent that at high concentrations can cause dizziness, headache, sleepiness, confusion, nausea, difficulty speaking and walking, unconsciousness and sometimes death, according to the Agency for Toxic Substances and Disease Registry. It is classified as a carcinogen by the Department of Health and Human Services.
After PCE was discovered at Topps, the New Jersey Department of Environmental Protection required that additional remedial investigations be conducted there. However, the site's owner failed to perform them. It wasn't until the late 1990s, when unrelated remedial investigations found PCE contamination outside of the boundaries of the Topps site, that the NJDEP concluded Topps Cleaners was the source of both on-site and off-site PCE contamination.
In May 2003, the NJDEP directed Topps' owner to investigate the site and develop a cleanup plan. AMAI was hired to perform the investigation.
Through their investigation, AMAI discovered that PCE contamination in the soil beneath the Topps building had migrated into groundwater and off-site into the surrounding residential neighborhood.
Approximately 90 on-site and off-site ground water monitoring wells have been installed and sampled since the investigation began in order to determine the range and extent of the contamination.
Analyses found that PCE plumes have spread approximately 2,400 feet from the Topps site in a southeasterly direction beneath Archery Plaza and east of Plaza Road, and approximately 1,400 feet south-southwest toward 20th Street.
Some homes in the area have experienced PCE vapor intrusion, which occurs when fumes from the PCE-contaminated soil or ground water seep through cracks in the foundations of buildings and accumulate in basements, crawl spaces or living areas.
Through six phases of testing, a total of 71 homes along Plaza Road, Townley Road, Ramapo Terrace, Ramsey Terrace, Reading Terrace and Randolph Terrace were investigated for vapor intrusion.
Of those 71 homes, 15 were found to have PCE vapors at concentrations that exceeded NJDEP's residential screening levels. Those homeowners were given the option of having AMAI install sub-surface depressurization systems to prevent PCE vapors from entering the home.
In 2008, AMAI sought to eliminate the contamination source by treating the PCE-contaminated soil and groundwater directly beneath the Topps site using a process called electrical heating resistance.
It was the first time this particular technology had been used at a site in New Jersey.
“We put in giant electrodes, rods we drilled in down to 28 feet so that they’re at the top of the bedrock," Ivens said, explaining the electrical heating resistance process. "When you put a current between these rods, these electrodes, the current heats up the soil and the soil moisture and it vaporizes the contamination...We captured all the vapor, all the steam that was coming off and sent it through carbon filter system and so forth to clean it up."
The procedure, which removed the on-site source of PCE, reduced on-site soil PCE levels by 99.9 percent and on-site groundwater PCE levels by more than 95 percent.
With the source removed and no longer able to contribute to the spread of PCE off-site, AMAI projects the levels of PCE in the groundwater to naturally taper off over time until about 2052, when groundwater across the entire affected area will meet NJDEP standards.
“There’s nothing new that can come in," Ivens said. "Whatever was creating the plume has been completely removed. There’s PCE left in the groundwater, but because we did the treatment and the heating, it’s breaking down. And we’re seeing natural breakdown, in the other edges of the well, so it’s shrinking from both sides."
AMAI will continue monitoring the wells quarterly over the next forty years, or for as long as it takes for the groundwater contamination to subside.
"We will be out there monitoring and modeling and sampling to make sure that the processes are working the way that we expect them to," Ivens said. "We have to recertify [with the NJDEP]…to reestablish the [Classification Exception Area] every two years. And as part of this process too, we will be filing semi-annual progress reports, which I will put in the library…so you will have access to the data.”
For answers to some Frequently Asked Questions about the Topps site contamination, click here.